I'm in Scotland. Looking outside and seeing blue skies does not mean it's safe to leave without a rain jacket, or a thermal layer. Seeing fog in the morning doesn't mean you don't need shorts for the afternoon. It being 0 outside today doesn't mean it won't be 10 degrees tomorrow. Knowing it's going to rain between 10 and 2 is good motivation to take the dog out before 10. Knowing it's going to rain on Sunday but be clear on Saturday is a good reason to book outdoor activites (golf) on Saturday instead.